Estimated impact of the UK soft drinks industry levy on childhood hospital admissions for carious tooth extractions: interrupted time series analysis

The impact of the UK soft drink industry levy on the soft drink marketplace, 2017-2020: An interrupted time series analysis with comparator series

BACKGROUND

In April 2018, the UK government implemented a levy on soft drinks importers and manufacturers, tiered according to the amount of sugar in drinks. The stated aim was to encourage manufacturers to reduce sugar and portion sizes. Previous evidence suggests that the policy has been successful in reducing sugar in drinks in the short-term since implementation, but their sustained effects have not been explored. This study aimed to assess the impact of the soft drink industry levy (SDIL) on sugar levels, price, portion size and use of non-sugar sweeteners in the medium-term.

METHODS AND FINDINGS

Product data from 30 November 2017 to 14 March 2020 from one major UK retail supermarket were analysed (112,452 observations, 126 weekly time points). We used interrupted time series analysis, to assess the impact of the soft-drink industry levy (SDIL) on levy-eligible soft drinks, with exempt drinks (i.e. 100% fruit juices, milks, flavoured milks) acting as a comparator series. At the point of implementation of the SDIL (April 2018) there was a step change in the proportion of eligible drinks with sugar content below the SDIL levy threshold (5g per 100ml) (+0.08, 95%CI: +0.04, +0.12), with a similar sized decrease in the proportion in the highest levy category (> = 8g sugar per 100ml) (-0.06, 95%CI: -0.10, -0.03). Between April 2018 and March 2020, the proportion of eligible drinks below the SDIL levy threshold continued to gradually increase (p = 0.003), while those in the highest levy category decreased (p = 0.007). There was a step change in price of eligible drinks in the higher levy category at the point of implementation of +£0.049 (95%CI: +£0.034, +£0.065) per 100mL (for comparison, the levy is set at £0.024 per 100mL for this group). Trends in price for the high levy category were not altered by the SDIL. In the no levy category, there was a step change in price at the implementation (+£0.012 per 100mL, 95%CI: +£0.008, +£0.023), followed by a second step change in October 2018 (-£0.018p per 100mL, 95%CI: -£0.033, -£0.001p). The volume of products in the higher levy group decreased at the time of the implementation (-305mL on average including multipacks, 95%CI: -511, -99). The change in trend for the product volume of drinks in the higher levy group between April 2018 and March 2020 was in the increasing direction (+704mL per year, 95%CI: -95, 1504), but it did not meet our threshold for statistical significance (p = 0.084). There were no changes observed in the volume of lower levy drinks or no levy drinks. There was a step change in the proportion of drinks with non-sugar sweeteners at the implementation of the SDIL (+0.04, 95%CI: +0.02, +0.06).

CONCLUSION

These results suggest that the SDIL was successful in [1] producing reductions in sugar levels that were maintained over the medium term up to March 2020 and [2] a reduction in product volume for higher tier drinks that may be diminishing over time. Our results also show that the SDIL was associated with a maintained price differential between high and low sugar drinks.

Outcomes of sugar reduction policies, United Kingdom of Great Britain and Northern Ireland

Poor diets are the major cause of death and disease globally, driving high levels of obesity and noncommunicable diseases. Cheap, heavily marketed, ultra-processed, energy-dense and nutrient-poor food and drinks that are high in fat, sugar and salt play a major role. The high-sugar content of these products leads to consumption levels much higher than recommended. The World Health Organization recommends that sugar intake should be reduced to just 5% of energy intake by using fiscal policies and food and drink reformulation strategies. Over the previous decade, the government of the United Kingdom of Great Britain and Northern Ireland has implemented several policies aimed at reducing sugar intake. We compare the soft drinks industry levy and the sugar reduction programme, examining how differences in policy design and process may have influenced the outcomes. Success has been mixed: the mandatory levy achieved a reduction in total sugar sales of 34.3%, and the voluntary reduction programme only achieved a 3.5% reduction in sugar levels of key contributors to sugar intake (despite a target of 20%). Both policies can be improved to enhance their impact, for example, by increasing the levy and reducing the sugar content threshold in the soft drinks industry levy, and by setting more stringent subcategory specific targets in the sugar reduction programme. We also recommend that policy-makers should consider applying a similar levy to other discretionary products that are key contributors to sugar intake. Both approaches provide valuable learnings for future policy in the United Kingdom and globally.